This morning I gave my own talk at Rethinking Agricultural Systems. It is based on a paper now in press at Conservation Letters (pre-final version here). I don’t have a “script” of my talk, but I have my slides, which I thought I’d share with you here.

7 responses to “Land sparing versus land sharing: moving forward”

Really interesting analysis, thanks Joern. The only thing I’d add is that of course some agriculture is dependent on wild biodiversity, animal pollination of a range of crops being the obvious one. So in this context having a landscape which integrates patches of natural or semi-natural habitat with agricultural areas is essential. In Europe we are trying to retro-fit such habitat into very intensive agricultural settings (e.g. growing wild flower margins, restoring high diversity meadows) but with variable success. Such landscapes would sit within the middle of your gradient and I suppose would be considered land sharing. But it’s sharing with a subset of “desirable” biodiversity; anything “undesirable” (e.g. predators, mass flocking seed eaters) would be discouraged/killed.

So that sharing has conditions attached to it by whoever is managing the land, potentially leading to a very different local ecology than if the area was “spared”. Does that bother you? Is that a trade-off which is acceptable in your view? I think it is as long as the “undesirable” biodiversity has space in which to establish populations in other parts of the landscape. But in some parts of the world (e.g. Britain!) that may not be possible and ultimately you lose species/guilds, as we have done.

Thanks Jeff. As I pointed out in my 2008 paper I think in real-world landscapes, often it’s a mix of what you need. And indeed, you may need landscape-specific measures both for unwanted species, and for those particularly threatened (I wrote about that in a paper in 2006 — see here). So typically, I agree that it’s a mix that will probably work best. Hope my response makes sense! Cheers — J.

If I may weigh in, the comment “So that sharing has conditions attached to it by whoever is managing the land, potentially leading to a very different local ecology than if the area was “spared”” is very interesting, because this is clearly true–but exactly *how* and *what* area were “spared” is also very interesting. Is it likely, under any circumstance, that areas with very intensive landscapes would be very amenable to “sparing”? You seem to be referring to organisms that exist within this landscape (predators, mass flocking seed eaters being killed), so to “spare” them, land in this particular landscape would have to be set aside for them. *And under the assumptions of a land-sparing model, a primary/important way to do this would be to increase the productivity in parts of that landscape (or other similar landscapes) and use that to relieve theoretical production pressure on the original landscape and set more of it aside as absolute preserves.* There are problems at each stage there — that productivity will decrease pressure, that socioeconomic, legal, political, and cultural circumstances are such that land can be effectively put in absolute preserves, and that such preserves will be effective in conserving biodiveristy if the areas surrounding the stay in (higher) intensity production.

So you’re quite right, Jeff, that there are trade-offs — but the trade-offs under even a working sparing regime including a possibly high degree of isolation of “spared” land, and the necessity to expropriate or buy off land to be preserved (not easy in the intensive landscapes in the US, at the very least), which will involve an interesting series of political trade-offs, and further, if these preserved areas are effectively conserving, say, predators and mass flocking seed eaters, they will serve as a source population into the surrounding sink of intensive agriculture and will thus still be seen as an absolute nuisance (probably) by adjacent land-owners.

This is a point (or series of them) that gets lost in sparing analyses, in my opinion–and it is important to remember in conversations that “sparing” does not simply equal “conservation/preservation set-asides”; sparing specifically proposes to relieve displacement and expansion pressure through increasing productivity on existing agricultural land. The degree to which the latter is necessary or desirable for conservation goals is variable and highly questionable, and this is my critique of “sparing”–the putative link between yield and land-use, which is far more complex than most sparing analyses originally acknowledged (though sophistication is growing).

Thanks for your comment Jahi. I’m coming to this as something of an interested outsider, a (mainly) terrestrial ecologist, working (mainly) on pollination ecology, with observations based on field work experience. As I see it, to some extent land is already “spared” in even intense agricultural landscapes, in gallery forests, steep slopes, rocky outcrops and other areas that can’t be cultivated. Clearly this is not intentionally for conservation purposes but it can have a positive conservation effect. However, as you say, “pest” species are generally not tolerated. Ideally there should be some kind of buffer between habitat that supports “pest” species and agricultural land, but that’s unlikely to work in most circumstances as many of these animals are highly mobile and land is scarce. It seems to me that decisions have to be made at a local level as what would be acceptable for one area would be unacceptable in others/ And also opinions about species change over time, the recent relegation of badgers in Britain to “undesirable on pastoral farmland” being one such example. Difficult (impossible?) to satisfy all stakeholders all of the time. Interesting questions to discuss though.

Thanks for the thoughtful response. I agree with practically all you say, but I still think that we need to be careful in terminology. I’ve seen plenty of areas not cultivated in intense agricultural landscapes, but the idea of “sparing” is directly connected to intensification (more output per area) in agriculture. As you say, many of those areas are not cultivated because it would not be easy to do so–a very different mechanism. The reason the distinction is important is because some interpretations of sparing, for example, would look to raise the productivity of the land in that landscape, which in many cases, we now know, would increase the incentives to *expand* into less-productive, harder-to-cultivate land. This has been observed empirically and shown to work according to economic theory, though this does not always happen.

So conservation, set-asides, all those things: absolutely. Decisions at a local level, I could not agree more. But calling uncultivated land “spared” can create confusion as many people still consider the intensification + more land in conservation idea to be empirically valid, despite accumulating evidence that it is not, as a general rule.